THE LAW WHICH UNDERLIES PROTECTIVE COLORATION. 481 



although told exactly where to look, failed to find any of the others 

 until within G or 7 yards, and even then only by knowing exactly 

 where to look. 



I had also painted bright blue and red spots as big as a silver quar- 

 ter of a dollar on the brown back of one of the graded eggs. These 

 spots the naturalist saw, when we had come pretty near, though they 

 only passed for details of the ground beyond the egg. 



It was to this latter experiment that I alluded iu a footnote when I 

 said that brilliant top colors scarcely tend to interfere with the grada- 

 tion's power. This statement does not apply, however, to creatures in 

 which, as in a bluejay, the bright color so predominates as to form a 

 silhouette shaped like the creature, but only when the bright pattern 

 goes, as it were, its own way, not accompanying the animal's form. 



Yet, even in the jay's case, his gradation down to white under throat 

 and belly diminishes so greatly his conspicuousness in the dim forest 

 shade that he may be suspected of great indebtedness to this arrange- 

 ment of color as he skulks among the leaves. He must often be much 

 helped, also, by the fact that whenever his gradation works its charm 

 and denies his substantiality his blue is likely, at least, to appear to 

 belong to whatever surface, far or near, forms his background for the 

 beholder's eye at the moment; as, for instance, a bit of blue distance 

 seen through the leaves. And often, when he is not concealed to this 

 degree, his ghostly appearance still tends to cause the beholder to think 

 him farther oft" than he is, which may be sometimes equivalent to con- 

 cealment. The reader should compare a graded blue egg with one blue 

 all over, both seen in deep woods. Let me urge the reader to under- 

 stand these color phenomena, which are the open door into a new world 

 of most charming study of special cases of protective coloration hith- 

 erto misunderstood. 



One must remember that by far the greater part of the objects he 

 espies as he walks are first caught sight of out of the side of his eye; 

 and it is this faint seeing against which all this faint appearing is so 

 potent in countless cases where the animal could not elude the direct 

 eye. In my former article I omitted to emphasize the device of nature 

 by which she accomplishes, in the only possible way, the bringing the 

 top, sides, throat, and belly of an animal to the exact color of the sur- 

 rounding earth, as well as to the same degree of darkness. 



The animal's top is brown like the ground about him, and from this 

 brown his color grades steadily colder till it becomes cold white on his 

 under surfaces. The latter, being in shadow and bathed iu a yellow 

 reflection from the earth, has the exact color as well as degree of dark- 

 ness of his top; since, obviously, earth-browu bathed in sky light 

 equals sky light (color^of the animal's belly) bathed in earth-yellow 

 and shadow, i. e., brown. 



This grading to white under surfaces is precisely what would result 

 if daylight tended to brown animals' coats and its lack to bleach them. 

 SM 07 31 



